Though their playful creations have graced Paris Fashion Week's catwalks for years, surprisingly enough, the Dutch design duo have never had a boutique in their home from home, the City of Light. That is, until now.

"Paris is our fashion home, it's our spiritual home," said Viktor Horsting from the sprawling basement floors of the all-gray space that opened this week. "That's why this is so great. It's our 20th anniversary this year. And opening this store is our way to mark this in a way to look forward, not back."

The store is certainly an impressive birthday present — about 7,000 square feet (650 square meters) of shop space over two floors on the prestigious rue Saint-Honore.

"Such a visible spot was for us the most important for our brand, especially in Paris," added Horsting.

The interior, described as "ghost architecture," is made up of curved architectural steel covered in a tactile, effacing soft gray felt. In a nice contradiction, it looks squishy, but is hard to the touch.

"We said to the architects we want a shop that's invisible," said Horsting. "When you enter you don't expect the huge space that opens up suddenly. It's a surprise."

The color gray was chosen to celebrate their history and symbolizes two decades since the designers founded their Amsterdam-based fashion house. Their first collection back in 1993 was also all-gray.

Looking back and taking creative stock might be a good idea for the designers, Horsting and his partner Rolf Snoeren, whose year was marked by a couple of ready-to-wear collections that had a rather lukewarm reception and were criticized by some for being unwilling to take creative risks.

The return to the couture stage, in July, after a 13-year hiatus, with a minimalist and meditative all-black collection was seen a welcome move that restored some of the artistic credibility the once-avant-garde designers have recently somewhat lost.